Animation Description
In the graphic that accompanies this question, images of seven animals, shark, tuna, frog, human, hare, caiman, and parrot, are connected by a branching evolutionary tree beneath them. An arrow shows that time progresses in the upwards direction on the tree. On the tree proceeding upwards, a blue horizontal line on the root indicates a potential ancestor in which the skull opening in front of the eye could have evolved. Then the branch leading to the shark splits off to the left. On the other branch (which leads to the remaining animals), another blue horizontal line appears. Then the branch leading to the tuna splits off to the left. On the other branch (which leads to the remaining animals), another blue horizontal line appears. Then the branch leading to the frog splits off to the left. On the other branch (which leads to the remaining animals), another blue horizontal line appears Then a branch splits off to the left that itself splits into two, leading to the human and hare. At the base of this branch, another blue horizontal line appears. The last branch, which extends up and to the right splits into the caiman and parrot branches. At the base of this branch, another blue horizontal line appears. At the top of the diagram a red line runs acorss the caiman and parrot lineages. When the blue line on the lineage representing the common ancestor of caimans and parrots is clicked, the other blue horizontal lines disappear, and the clicked line becomes red and is labeled "opening in front of eye." When any other line is clicked, the reader is instructed to "try again."
Animation Text
Panel 1
Click on the blue bar that best represents when the skull opening in front of the eye evolved.
Panel 2
Incorrect answer text: Oops. Here's a hint: the skull opening in front of the eyes evolved just before the caiman and parrot lineages split. Try again.
Panel 3
Correct answer text: Great! Now that you have an idea of how to map features on the cladogram, let's review.